a) Field of the Invention
The present invention is concerned with a method and apparatus used to create a virtual public numbering domain, which will coexist with and be parallel and non-intrusive to the existing geographic North American telephone network numbering plan.
b) Brief Description of the Related Art
Network facilitators have been unsuccessfully researching options for delivering a service where telephone numbers are not fled to equipment locations. For instance, in the existing network, each phone subscriber has a number in the NXX-NXX-XXXX format, where N represents a digit from 2-9 and X represents a digit from 0-9. The first group of three digits indicate the area code or NPA of the subscriber, the second group of three digits indicate a switching exchange or service switching point to which the subscriber is connected to, and the last group of four digits indicate the address of the subscriber within the service switching point.
Two telephone service applications of separating dialing from physical routing address are Local Area Portability and Abbreviated Dialing applications.
The Industry Numbering Committee (INC) 9 and 10 Number Portability workshops have studied the Local Area Portability application and received a submission from Electric Lightwave Inc. (ELI) in their document entitled "Local Area Number Portability (LANP) (an AIN 0.1 database service), by Sherman L. Ackley. It describes a new approach to number portability wig a metropolitain area using the Adavanced Intelligent Network 0.1 capabilities. This document was prepared to introduce the industry to the concept of implementing number portability on a metropolitain area basis, without affecting call routing by switches external to the LANP metropolitain area. The LANP precludes the availability to a caller of both direct North American Numbering Plan (NANP) dialling and Virtual Dialling by use of an explicit dialing code (the # key will be used throughout as an example of an explicity dialling code). Secondly, the ELI submission necessitates the overnight cutover of the entire exchange or metropolitan area, and the customer addresses must still adhere to the inflexible numbering format. Finally, the ELI approach forces all calls to query a database, which is impractical based on current network and database capacities.
The Information Industry Liaison Committe (IILC) is considering the Abbreviated Dialing application in its issue ESPR-036 entitled "Local calling area abbreviated dialing access to information and enhanced services", and has studied different possibilities with the objective being the ability for telcos to offer abbreviated or shortened dialling sequences within a local calling area. This committee agreed that the following four abbreviated dialling formats appeared more feasible from a technical and marketing standpoint: #XXX, #XXXX, NXX# and NXXX#, where # represents a symbol key on the telephone set, X represents digits 0 through 9, and N represents digits 2 through 9. This committee could not conclude on a method to provide the abbreviated dialling functionality but agreed that AIN developments should be planned to include functions to provide this service capability in AIN Release 1 (Subset 0.1 and 0.2) Their proposed dialling format is constrained to 10 000 possible subscribers and is limited to abbreviated dialing only.
BellSouth Telecommunications has contributed to the INC discussion on abbreviated dialing with their submission entitled "Recommendation of #XXX as a national abbreviated dialling plan" of Jun. 1, 1994. In this document, Bell South Telecommunications reviews the results of the Information Industry Liaison Committee (IILC) ESPR-036 and supports the use of #XXX with expansion to #XXXX as a national abbreviated dialing plan and further suggests that #XXX should be segmented into national and non-national numbers and administered by a single administrator. This document does not give any indication as to the method proposed to provide this abbreviated dialling plan or whether it could be made possible on the existing network. No introduction of a virtual address space was made or considered.
Also known in the art are special triggers for Advanced Intelligent Network (AIN) and any similar network. These triggers are divided in two classes: subscribed or originating triggers (which launch a query based on the callers phone number) and dialed or office triggers (which launch a query based on the dialed digits).
One trigger, known as the Customized Dial Plan trigger allows special dialling options to a subscriber or a group of subscribers known as a customer group (for example, 4-digit dialling within the company or group). This subscribed trigger is based on the calling number, and any special muting or service features is a function of the caller. This trigger is not practical for implementation of a public virtual dial plan because treatment of the call in the SCP must key on the calling number and thus service instructions would have to be present on the SCP for all possible callers rather than once for the dialed virtual address.
Another trigger is the Dialed Number (DN) trigger, which generalizes an 800 function so that any dialled number could launch a query rather than just 800 numbers. The trigger number is loaded on a single switch and the number format must conform to the existing NANP. The trigger is invoked when a call to that DN number arrives at the Service Switching Point (SSP) where a query is then lauched to the Service Control Point (SCP) for service handling. However adherence to the geographic routing plan is required, since the network must know to which exchange to route to based on area code and NXX exchange.
A third trigger is the public office dial plan (PODP), which is an office based trigger (query based on dialed digits but query launched from originating SSP). Because this trigger is loaded at the originating SSP, it is intended to be used by choosing ranges in the SSP for which queries are launched (it is generally understood that SCPs do not have the capacity to handle queries on all calls in an SSP). For instance, all 555-XXXX numbers could be sent to the SSP for treatment and thus the trigger is "Public". Somehow, all dialed ranges have to generate an SCP query.